A unified model for the formation and distribution of both conventional and unconventional hydrocarbon reservoirs

The discovery and large-scale exploration of unconventional oil/gas resources since 1980s have been considered as the most important advancement in the history of petroleum geology;that has not only changed the balance of supply and demand in the global energy market,but also improved our understanding of the formation mechanisms and distribution characteristics of oil/gas reservoirs.However,what is the difference of conventional and unconventional resources and why they always related to each other in petroliferous basins is not clear.As the differences and correlations between unconventional and conventional resources are complex challenging issues and very critical for resources assessment and hydrocarbon exploration,this paper focused on studying the relationship of formations and distributions among different oil/gas reservoirs.Drilling results of 12,237 exploratory wells in 6 representative petroliferous basins of China and distribution characteristics for 52,926 oil/gas accumulations over the world were applied to clarify the formation conditions and genetic relations of different oil/gas reservoirs in a petroliferous basin,and then to establish a unified model to address the differences and correlations of conventional and unconventional reservoirs.In this model,conventional reservoirs formed in free hydrocarbon dynamic field with high porosity and permeability located above the boundary of hydrocarbon buoyancy-driven accumulation depth limit.Unconventional tight reservoirs formed in confined hydrocarbon dynamic field with low porosity and permeability located between hydrocarbon buoyancy-driven accumulation depth limit and hydrocarbon accumulation depth limit.Shale oil/gas reservoirs formed in the bound hydrocarbon dynamic field with low porosity and ultra-low permeability within the source rock layers.More than 75%of proved reserves around the world are discovered in the free hydrocarbon dynamic field,which is estimated to contain only 10%of originally generated hydrocarbons.Most of undiscovered resources distributed in the confined hydrocarbon dynamic field and the bound hydrocarbon dynamic field,which contains 90%of original generated hydrocarbons,implying a reasonable and promising area for future hydrocarbon explorations.The buried depths of hydrocarbon dynamic fields become shallow with the increase of heat flow,and the remaining oil/gas resources mainly exist in the deep area of“cold basin”with low geothermal gradient.Lithology changing in the hydrocarbon dynamic field causes local anomalies in the oil/gas dynamic mechanism,leading to the local formation of unconventional hydrocarbon reservoirs in the free hydrocarbon dynamic field or the occurrence of oil/gas enrichment sweet points with high porosity and permeability in the confined hydrocarbon dynamic field.The tectonic movements destroy the medium conditions and oil/gas components,which leads to the transformation of conventional oil/gas reservoirs formed in free hydrocarbon dynamic field to unconventional ones or unconventional ones formed in confined and bound hydrocarbon dynamic fields to conventional ones.

Registration Based on ORB and FREAK Features for Augmented Reality Systems

This paper proposes a novel registration method for augmented reality (AR) systems based on Oriented FAST and Rotated BRIEF (ORB) and Fast Retina Keypoint (FREAK) natural features. In the proposed ORB-FREAK method, feature extraction is implemented based on the combination of ORB and FREAK, and the feature points are matched using Hamming distance. To get good matching points, cross-checks and least median squares are used to perform outlier filtration, and camera pose is estimated using the matched points. Finally, AR is rendered. Experiments show that the proposed method improves the speed of registration to be in real time; the proposed method can accurately register the target object under the circumstances of partial occlusion of the object; and it also can overcome the effects of rotation, scale change, ambient light and distance. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

青藏高原乡村人群对气候变化影响的感知与适应

青藏高原是全球气候变化的敏感区和脆弱区。研究青藏高原乡村人群对气候变化的感知与适应状况,对提高乡村人群气候变化的适应能力,促进青藏高原地区的社会稳定和可持续发展意义重大。本文采用问卷调查和访谈相结合的方式,分析了青藏高原乡村人群对气候变化感知与适应的现状。结果表明:在气候变化对农牧业的影响感知方面,68%的调查对象认为草场返青时间提前,62%认为在气候变化后草场状况恶化,78%认为农作物播种时间提前。在气候变化带来的不利影响感知方面,调查对象最担心的 3 个问题依次是:干旱更加严重(50.4%)、水资源矛盾突出(48.5%)、农业粮食安全(36.8%)。对气候变化的适应对策主要是:完善水利设施,采用高效节水灌溉技术(73.8%)、增加塑料地膜覆盖面或作物秸秆覆盖(58.2%)、调整农作物种植结构,改变作物布局(47.6%)。

Yttrium‐and nitrogen‐doped NiCo phosphide nanosheets for high‐efficiency water electrolysis

Engineering high‐performance and low‐cost bifunctional catalysts for H_(2)(hydrogen evolution reaction[HER])and O_(2)(oxygen evolution reaction[OER])evolution under industrial electrocatalytic conditions remains challenging.Here,for the first time,we use the stronger electronegativity of a rare‐Earth yttrium ion(Y^(3+))to induce in situ NiCo‐layered double‐hydroxide nanosheets from NiCo foam(NCF)treated by a dielectric barrier discharge plasma NCF(PNCF),and then obtain nitrogen‐doped YNiCo phosphide(N‐YNiCoP/PNCF)after the phosphating process using radiofrequency plasma in nitrogen.The obtained NYNiCoP/PNCF has a large specific surface area,rich heterointerfaces,and an optimized electronic structure,inducing high electrocatalytic activity in HER(331mV vs.2000mA cm^(−2))and OER(464mV vs.2000mA cm^(−2))reactions in 1MKOH electrolyte.X‐ray absorption spectroscopy and density functional theory quantum chemistry calculations reveal that the coordination number of CoNi decreased with the incorporation of Y atoms,which induce much shorter bonds of Ni and Co ions and promote long‐term stability of N‐YNiCoP in HER and OER under the simulated industrial conditions.Meanwhile,the CoN‐YP_(5) heterointerface formed by plasma N‐doping is the active center for overall water splitting.This work expands the applications of rare‐Earth elements in engineering bifunctional electrocatalysts and provides a new avenue for designing highperformance transition‐metal‐based catalysts in the renewable energy field.

Determination of gas adsorption capacity in organic-rich marine shale: a case study of Wufeng-Lower Longmaxi Shale in the southeast Sichuan Basin

Determination of gas adsorption capacity under geological conditions is essential in evaluating shale gas resource potential.A quantitative determination of gas adsorption capacity was proposed through 1)investigating controlling geological factors(including both internal ones and external ones)of gas adsorption capacity in organic-rich marine shale with geochemical analysis,XRD diffraction,field-emission scanning electron microscopy,and methane sorption isotherms;2)defining the relationship between gas adsorption capacity and single controlling factor;3)establishing a comprehensive determination model with the consideration of all these controlling factors.The primary controlling factors of the sorption capacity for the studied O3wLower S1l shale are TOC,illite and quartz,temperature,pressure,Ro,and moisture(water saturation).Specifically,TOC,thermal maturity,illite,and pressure are positively correlated with sorption capacity,whereas,quartz and temperature contribute negatively to the sorption capacity.We present the quantitative model along with application examples from the Wufeng-Lower Longmaxi Shale in the southeast Sichuan Basin,west China,to demonstrate the approach in shale gas evaluation.The result shows that the comprehensive determination model provides a good and unbiased estimate of gas adsorption capacities with a high correlation coefficient(0.96)and bell-shaped residues centered at zero.